When semiconductor parts, flat display panels, and electronic components are manufactured, a substrate process system has been conventionally used for cleaning and etching objects to be processed, such as semiconductor wafers, liquid crystal substrates, and disc-shaped storage mediums, with the use of a process liquid.
The conventional substrate process system includes a process liquid supply system that supplies a process liquid formed by diluting a chemical liquid with a pure water to a process vessel, for processing an object to be processed. In the process liquid supply system, a chemical liquid pressurized by a compressed gas is diluted with a pure water to produce a process liquid of a predetermined concentration.
To be specific, in the conventional process liquid supply system, a pure water supply source is connected to the process vessel through a supply pipe. There is also disposed a chemical liquid tank that stores a chemical liquid, and supplies the chemical liquid stored therein to the supply pipe through a mixing valve. A compressed gas supply source is connected to the chemical liquid tank through a compressed gas supply pipe.
In the conventional process liquid supply system, the chemical liquid (e.g., hydrogen peroxide, ammonia, hydrochloric acid, or hydrogen fluoride) stored in the chemical liquid tank is supplied to the supply pipe by a predetermined pressure of the compressed gas (e.g., nitrogen gas) supplied from the compressed gas supply source. Inside the mixing valve, the chemical liquid is diluted with a pure water supplied form the pure water supply source at a predetermined concentration so as to produce a process liquid. The thus produced process liquid is supplied to the process vessel (see, for example, JP2001-157833A).